Bullrush/how to kill it

We have wrp project that is about 10 years old. for the first 6-7 years we had no problems with cattail or bullrush. the last two years both have exploded. Depth is anywhere from 2 inches to 4 feet (agridrain) We can not drain it completely due to ground water. My dad has a restricted use lisc. and we have been knocking the heck out of the cattail and the arrowhead that is starting to pop up. I sprayed everything this spring (early june) and again about 2 weeks ago (roundup custom per the nrcs). The bullrush looks like i never touched it. The second time I mixed it really hot and used coop surfractant. Any ideas on what else to use?

Glyphosate herbicide is the most effective herbicide for bulrush control. Unlike contact herbicides that work on the surface of a plant, glyphosate is a systemic herbicide that absorbs inside the stem and is translocated to the rhizomes to kill the entire plant and not just the stems. This is a rather slow process that is made much faster with the addition of a non-ionic surfactant which helps the product coat the stems and penetrate more easily. Chemical control is most effective when you apply the herbicide immediately after flowering but before seeds develop. It takes roughly two weeks for the glyphosate to desiccate the stems and completely kill the bulrush.

Applying Gyphosate to Bulrush

While many weedkillers contain glyphosate, only use a product labeled for use on aquatic plants for bulrush. Mix the glyphosate in a garden sprayer at a rate of 2 ounces to 1 gallon of water, or according to the label's instructions. Add a non-ionic surfactant at a rate of about 1 teaspoon per gallon of water. Spray the herbicide along the length of the stems until they're well coated, but not so heavy that the liquid runs off the stems into the water. Treat no more than one-fourth of the bulrushes in one session, particularly if there are other plants or aquatic wildlife in the pond because the dying plants can deplete the oxygen in the water, killing fish and other creatures in the pond. When the bulrushes have died, remove them from the pond.

Hannibal, I did exactly that. But I mixed it almost 8 oz per gal. Used the non ionic surfactant. I was frustrated that 5 oz per gal didnt do the job the first time so I mixed it pretty hot. bbfky, I will look into that, thanks.

I have used glyphosate with good success this yr. My recommendation is to mix it twice as much as it calls for and make sure you get good coverage. The hotter the weather the better. Its a little expensive but do it right once and save the hassle